You could try some Dayton HO 10s if your box is sealed. They love small sealed and small ported boxes. You can find them at
parts express. Rated at 600 or 700 rms cant remember ATM, but I own some in a ported box tuned to 29hz and the SQ is AMAZING! and they will get pretty nasty if I crank it too. I can still shut down alot of the BS systems around me. The type R's are also nice SQL subs but idk how well they do sealed. heres a link:
Dayton Audio RSS265HO-4 10" Reference HO Subwoofer 4 Ohm 295-462
For amps, look into boston Acoustics namely this one:
Boston Acoustics GTA-704 (GTA704) 4-Channel Class AB GTA Amplifier for your mids and highs (also could look into MB Quart)
for your lows, since you want new,
http://www.amazon.com/Boston-Acoustics-GTA-800m-subwoofer-amplifier/dp/B002R5YKJI but you may need more power to get better volume sealed. (or once again try mb quart)
Mids n Highs: I've heard good things about the Type R's, I have a set of Pioneer TSD1720cs that are some of the best budget comps I've ever owned and many others will agree, also look into the Morel Maximo, and since Im obviously a boston acoustics fan, the S-series up to the SC series might be good for you to look into.
Quick math tells me this surpasses your $730 budget though lol But I know the MB Quart amps are less expensive than the Bostons i recommended but I cannot personally attest to their performance like i can with BA.
Used may not really be a bad idea, but I understand wanting to buy new so maybe you could do a little at a time....?